The primary aim of this project is to develop objective measures for evaluation of mild and moderate Traumatic Brain Injury (MTBI) using advanced MR neuroimaging methods. MTBI represents a major public health problem for which the current assessment measures are limited in their ability to quantify the severity of injury or to indicate possible outcomes. The pilot period of this project has demonstrated that Volumetric Magnetic Resonance Spectroscopic Imaging (MRSI) at 3 Tesla can detect widespread metabolic changes in the brain that correlate with the degree of injury, even for mild injury and in the absence of significant structural MRI findings. It is now proposed to extend this study to improve characterization of these changes and to evaluate the use MRSI and diffusion-weighted MRI measures for prognosis of functional outcomes following mild and moderate closed-head injury. Measurements will include N-Acetylaspartate and choline, metabolic markers known to be sensitive to neuronal dysfunction and membrane turnover, and Fractional Anisotropy, which reflects the degree of neuronal organization. Results will be correlated with findings from structural MRI, initial clinical assessments, and neuropsychological evaluation of functional outcomes at multiple time points after injury. A secondary aim of this study is to examine possible associations between post- concussive symptoms, which are debilitating and persistent consequences in a fraction of this patient group, and neuroimaging measures. A third aim is to optimize the quantitative and multiparametric neuroimaging measures to improve characterization of the spatial extent and the degree of metabolic consequences of the injury, and their associations with functional outcome measures. It is hypothesized that the improved sensitivity and spatial coverage of the proposed neuroimaging measures will improve characterization of mild and moderate injury.